Brightness Control Apparatus and Brightness Control Method

1. A brightness control apparatus adapted to control brightness of a display of an electronic device, and the brightness control apparatus comprising: a conversion unit converting a first pulse width modulating signal into a DC signal, wherein the first pulse width modulating signal indicates the brightness of the display; and an analog to digital conversion unit coupled to the conversion unit and converting the DC signal into a second pulse width modulating signal according to an environmental condition and a load state of the electronic device, wherein the second pulse width modulating signal controls the brightness of the display; wherein the analog to digital conversion unit further generates a duty ratio according to the environmental condition and the load state of the electronic device, and converts the DC signal into the second pulse width modulating signal according to the duty ratio; and wherein when the electronic device is in a heavy load state, the analog to digital conversion unit adjusts the duty ratio of the second pulse width modulating signal to adjust the brightness of the display to be lower than a preset low brightness.

2. The brightness control apparatus as claimed in claim 1 , wherein the environmental condition comprises an ambient temperature, and when the ambient temperature is higher than a first preset temperature or lower than a second preset temperature, the analog to digital conversion unit adjusts the duty ratio of the second pulse width modulating signal to adjust the brightness of the display to be lower than a preset low brightness.

3. The brightness control apparatus as claimed in claim 1 , wherein the environmental condition comprises an ambient light intensity, and when the ambient light intensity is higher than a preset light intensity, the analog to digital conversion unit adjusts the duty ratio of the second pulse width modulating signal to adjust the brightness of the display to be higher than a preset high brightness.

4. The brightness control apparatus as claimed in claim 1 , wherein the conversion unit comprises: a band pass filter unit performing band pass filtering on the first pulse width modulating signal; and a low pass filter unit coupled to the band pass filter unit and the analog to digital conversion unit, and performing low pass filtering on a signal of an output terminal of the band pass filter unit to generate the DC signal.

5. The brightness control apparatus as claimed in claim 4 , wherein the band pass filter unit comprises: an operational amplifier, having a positive input terminal coupled to a reference voltage; a first resistor coupled to a negative input terminal of the operational amplifier; a first capacitor, coupled between the negative input terminal of the operational amplifier and a ground; a second resistor; and a second capacitor, connected in parallel with the second resistor between the negative input terminal and an output terminal of the operational amplifier.

6. The brightness control apparatus as claimed in claim 4 , wherein the low pass filter unit comprises: a resistor, coupled between the output terminal of the band pass filter unit and an output terminal of the low pass filter unit; and a capacitor, coupled between the output terminal of the low pass filter unit and the ground.

7. A brightness control method adapted for a display of an electronic device, the brightness control method comprising: converting a first pulse width modulating signal into a DC signal, wherein the first pulse width modulating signal indicates brightness of the display; and converting the DC signal into a second pulse width modulating signal according to an environmental condition and a load state of the electronic device, wherein the second pulse width modulating signal controls the brightness of the display wherein the step of converting the DC signal into the second pulse width modulating signal according to at least one of the environmental condition and the load state of the electronic device comprises: generating a duty ratio according to the environmental condition and the load state of the electronic device; and converting the DC signal into the second pulse width modulating signal according to the duty ratio; and wherein when the electronic device is in a heavy load state, the duty ratio of the second pulse width modulating signal is adjusted to adjust the brightness of the display to be lower than a preset low brightness.

8. The brightness control method as claimed in claim 7 , wherein the environmental condition comprises an ambient temperature, and when the ambient temperature is higher than a first preset temperature or lower than a second preset temperature, the duty ratio of the second pulse width modulating signal is adjusted to adjust the brightness of the display to be lower than a preset low brightness.

9. The brightness control method as claimed in claim 7 , wherein the environmental condition comprises an ambient light intensity, and when the ambient light intensity is higher than a preset light intensity, the duty ratio of the second pulse width modulating signal is adjusted to adjust the brightness of the display to be higher than a preset high brightness.